As this is true of all perishable food articles, as well as of poultry products, the growth of cities was restricted as long as there was no means of bringing provisions quickly from places where they could be produced at low cost. When steam railroads were built, this restriction on the growth of cities was partly removed. Many cities then began to grow very fast, and the demands of their population for cheap food led city dealers in provisions to look for supplies in the towns and farms along the railroads. Many such dealers had before collected provisions by wagon as far from the city as was practicable. These men could now greatly extend their routes, because, having collected a wagon-load, they could take it to the most convenient railway station, ship it by rail to the city, and go on collecting, instead of spending a day or more in delivering their load in the city. Very soon after railroads were first built, many farmers began to produce more poultry and eggs and to ship them directly to the best city market that they could find. As the demand for their produce was usually much greater than could be supplied from their own farms, such farmers often began to buy from their neighbors, thus becoming middlemen as well as producers. In many cases such men would after a time find it to their advantage to move their headquarters to the city, and would ultimately build up a very large business. [Illustration: Fig. 226. Fattening chickens in crates at a poultry buyer's warehouse.[25] (Photograph from the Bureau of Chemistry, United States Department of Agriculture)] [25] If the farmer sells his chickens without fattening, the buyer can fatten them in this way and so make an extra profit. In nearly all farming sections, even those most remote from city markets, there is a short period in the spring when there is a large surplus of eggs and sometimes a period in the fall when there is more poultry ready for market than can be sold; but the people in those places rarely make any effort to increase their production, and to extend the seasons when they have more than enough for themselves, until they have good facilities for shipping eggs and poultry and the demands from outside cause a marked increase in the local prices of these products. [Illustration: Fig. 227. Driving turkeys to market. (Photograph from Bureau of Chemistry, United States Department of Agriculture)]